Spark Plug Wire Buyer's Guide
- A spark plug wire is an electrical cable that channels high voltage pulses from the ignition coil in select types of ignition systems.
- Spark plug wires feature thick outer insulation made of a heat-resisting flexible material such as silicone or synthetic rubber.
- Normally, you can reach 100,000 miles with no troubles with your spark plug wire while some can reach up to 120,000.
- The easiest way to know when to change a spark plug wire is by examining the ignition system after experiencing a drop in performance or, usually, a misfire.
- Spark plug wires vary in length. The spark plug that’s farthest to the distributor has the longest wire.
- Do not touch the spark plug wire when your engine is running as even a small opening can send tens of thousands of volts that can electrocute you.
- A single-piece spark plug wire would cause you $4 while the most expensive one you can buy is a set of 16 worth $340.
The ignition system is one of the most important systems in a car because, without it, your car won’t start and run smoothly. The ignition system aids combustion by generating sparks in the combustion chambers to ignite the compressed air and fuel mixture. It does this through the help of spark plugs.
For these spark plugs to create an arc of electric current between the electrodes, special high-tension cables need to connect them to the distributor or ignition coil. These cables are spark plug wires.
What does a spark plug wire do?
A spark plug wire, also called a high-tension lead or spark plug cable, is an electrical cable that channels high-voltage pulses from the ignition coil in select types of ignition systems. The electric pulses from the ignition coil travel through the coil wire towards the distributor, which then distributes them to the spark plugs via the spark plug wires. It is the pathway in which the electric pulses travel to reach the electrodes of the spark plug.
Compared to typical wires, plug wires are built to have a lot of resistance. This resistance greatly reduces the radio static being generated by the ignition system. A standard plug wire has a resistance of about 10,000 to 15,000 ohms per foot of length--if it's measurably higher, the wire will probably malfunction.
It's worth noting that spark plugs do not actually create heat but only remove it. Working as a heat exchanger by pulling unwanted thermal energy away from the combustion chamber, spark plugs transfer the heat to the engine's cooling system. The spark plug's firing end temperature must be kept at optimum levels to prevent pre-ignition and fouling.
How long do spark plug wires last?
Spark plug wires feature thick outer insulation made of a heat-resisting flexible material such as silicone or synthetic rubber. Depending on the manufacturer, this insulation comes in layers and with an external sheath. At both ends are terminals for the distributor or ignition coil and spark plug. These terminals receive protection from insulating terminal boots.
But just how long do these high-tension cables last, you ask? Some can reach up to 120,000 miles without needing a fix, while the typical longevity is around 100,000. This, however, can get affected by several factors that can shorten its lifespan.
However, the longer the spark plug wires are in service, the more brittle its insulation gets and the core also develops cracks. The resulting breakdown in the spark plug wire means the electricity will be redirected elsewhere, causing engine misfiring, fouled spark plugs, and rough running. Unfortunately, spark plug wire problems can be hard to detect since spark plug wire insulation and core problems are hidden below the spark plug wire surface.
When to change a spark plug wire
Normally, you can reach 100,000 miles with no troubles with your spark plug wire. However, it doesn’t happen all the time since anything can happen, especially to a component that’s consistently handling 12,000 to 30,000 volts. A bad spark plug wire can interrupt the flow of electricity and may prevent the spark plug from firing completely. This can lead to many problems in your ignition system.
The easiest way to know when to change a spark plug wire is by examining the ignition system after experiencing a drop in performance or, usually, a misfire. Mechanics use an advanced tool called the ignition scope or digital storage oscilloscope (DSO) which can detect a bad spark plug wire.
For engine misfires, you can use a spark plug tester. This tool can artificially increase the firing voltage of the spark plug, which is helpful if you’re trying to troubleshoot your ignition system.
Other symptoms of a failing spark plug wire include:
- Rough idling
- Hesitation during acceleration
Take note that these symptoms do not always stem from bad spark plug wires. Be sure to carefully diagnose the problem before replacing a specific part. It is advisable to visit a certified mechanic who can evaluate the condition of your car and properly assess the problem.
Simple Tips in Purchasing a Spark Plug Wire
Changing your spark plug because you think it doesn't provide enough spark inside the cylinder? While you're at it, why don't you check your spark plug wire too? If the wire's insulator is already worn out, the electricity that passes through it might arc to other metal components in your engine-which causes a weak or no spark at all. Now, if you would have to replace it, make sure that you'll get the ideal aftermarket spark plug wire for your car. And here's how to spot one:
Check the durability
Look for a spark plug wire that has a heavy-duty insulator. Basically, if the rubber outside the wire is in good condition, there's nothing wrong with your spark plug wire. You can guarantee that it would stay that way for a long time by acquiring a replacement wire that has a durable insulator. A spark plug wire with a high-strength silicone-made insulator would be a great choice since it can withstand the wear and tear that comes with constant exposure to extreme engine heat, moisture, and more.
Pick a spark plug wire that would fit your engine. Make sure you don't waste your time and money on a replacement wire that doesn't fit your vehicle's make and model. Check the features of the product if it's an OE replacement to guarantee two things: it can directly replace your factory-installed wires and can be installed with so much ease.
Double-check the warranty
Since you won't actually know if it would last until it's already under your hood, you have to buy a replacement wire that has a decent warranty. That way, you can quickly return it to the store where you bought it and get it replaced if it wears out prematurely. The spark plug may come with a 5-year or 50, 000 miles limited warranty or a 1-year unlimited mileage warranty depending on the brand or retailer.
Make sure to get the right quantity
Know how many wires you would have to replace. If you only need to change one wire, you can look for an online shop that sells a spark plug wire individually. Buying a set doesn't make sense because you wouldn't use the other wires. The only way that you would need a set is when you have to replace two or more defective spark plug wires.
How much is an aftermarket spark plug wire replacement?
It is important that your spark plug wire replacement is durable enough to last long or reach the lifespan of an OEM-made cable. So CarParts.com only offers quality parts from reputable brands in the market, and for a low price. A single-piece spark plug wire would cause you $4 while the most expensive one you can buy is a set of 16 worth $340.
Finding the right fit
The thing with spark plug wire replacements is that they come in different lengths to match specific ignition system layouts. Make sure you do your research if you’re planning on replacing your spark plug wires. Fortunately, finding the right spark plug wire replacement on CarParts.com is easy. Just plug in your vehicle’s year, make, and model and you can browse all products that fit your ride.
Replacing a spark plug wire
Spark plug wires vary in length. The spark plug that’s farthest to the distributor has the longest wire. Each wire has a metal terminal or boot that clips onto the spark plug, distributor, or ignition coil on older vehicles. Disconnecting these terminals requires a special tool known as the spark plug pliers.
Do not touch the spark plug wire when your engine is running as even a small opening can send tens of thousands of volts that can electrocute you. What you can do is refer to your owner’s manual or have it replaced by a proper technician.
How to Change Worn-out Spark Plug Wires by Hand
You read that right. You can change your faulty spark plug wires without using any tools at all. Unlike other automotive repairs that you've done before, this particular car part replacement won't require you to use even the most basic hand tools in your toolbox. In short, your hands are enough to get the job done. How to do that? Well, just follow the simple set of instructions below.
Difficulty level: Easy
Things that you'll need:
- Replacement spark plug wires
Step 1: Locate the spark plug wires. Although they're usually black, they can also be blue, orange, or red.
Step 2: Start by removing the first spark plug wire at one end of the engine. Pull the boot off of the wire plug.
Step 3: Pull the other end of the spark plug wire from its connection to the distributor.
Step 4: Replace the worn-out spark plug wire with a new one with the same length or number. When it snaps on the spark plug, you will hear a faint popping sound-which basically means that it's secured.
Note: Normally, the wires are kept in place by small plastic pieces with slots that prevent them from rubbing against each other. Make sure that the replacement wires are carefully placed into the slots to maximize their lifespan.
Step 5: Repeat steps 2 to 4 in replacing the next spark plug wire.